Oil pump for combustion engines



March 23 1926.

1,577,590 G. J. RATHBUN OIL PUMP FOR COMBUSTION ENGINES Filed A ril zs, 1924 5 Sheets-Sheet 1 HIS ATTOR.N Y

March 23,1926. 1,577,590

' G. J. RATHBUN OIL PUMP FOR COMBUSTION ENGINES Filed April. :25, 1924 3 Sheets-Sheet 2 a:

r, qw etmam 33? 9-140 abtozn% March 23 1926.

G. J. RATHBUN OIL PUMP FOR COMBUSTION ENGINES Filed April 25 1924 s Sheets-Sheet 5 HIS ATToN Y Patented Mar. 23, 1926.

UNITED STATES PATENT OFFICE.

GEORGE J. RATHBUN, OE TOLEDO, OHIO, ASSIGNOR'TO INGERSOLL-RAND COMPANY, OF

JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY, .J'OINTLY WITH THE.

RATHBUN-JONES ENGINEERING COMPANY, A CORPORATION OF OHIO.

OIL, PUMP FOR COMBUSTION ENGINE S.

Application filed April 25, 1924. Serial No, 708,837.

This invention relates to oil engines but more particularly to pumps for injecting oil unmixed with air into the cylinders of such engines commonly 'known as solid injection pumps.

In multi-cylinder oil. engines, it has been. found expedient'to inject the fuel into combustion chambers of the cylinders by means of a single pump and a device for distributing the fuel at the proper times to the various cylinders. In order to provide the proper number of fuel injections into the cylinders, the pump is operated at a rate higher than the crank shaft speed, the pump speed depending upon the number of cyl inders. The pump speed in the case of en,- gines having six or more cylinders becomes comparatively high as,'for instance, in the 'case of a six-cylinder motor operating on the four-stroke cycle at500 R. P. M., the pump plunger will reciprocate at the rate of 1500 times per minute in order to provide the necessary six injections during each two revolutions of the crank shaft. This high pump speed-introduces a difficulty in operatmg any pump construction which is not present at lower speeds. The use of cams for guiding the pump plunger at" a high speed has been found to be not entirely satisfactory as the parts used to operate the pump plunger must be made heavy and cumbersome and the wear on the cam is ex cessive. A means more preferable than cams for this use is an eccentric and a direct connected push rod. This permits the use of a cross head associated with the pump plunger to actuate and guide the pump plunger. The use of an eccentric introduces a difficulty in that the pump plungeris continuously moving in a slmple, harmonic motion and, consequently, the pumping stroke is of too long duration. An additional difiiculty is introduced by the fuel distributor for the reason that there are periods when the oil passage is completely blocked and at such times a high pressure on the pump would be apt to ruin parts of the distributor. This difficulty is not present when a cam of theproper shape is used but, with the exception of certain special cases, certain parts of the pump stroke must be rendered ineffective when this plunger is operated by an eccentric.

It is, accordingly, the object of the invention to enable the pump plunger to be operated by' an eccentric and to render ineffective certain portions of the pumping stroke to obviate the difiiculties above referred to.

Further objects of the invention will be in part obvious and'in part pointed out hereinafter.

In the drawings forming part of this I specification and in which similar reference characters refer to similar parts,

Figure 1 is a side elevation of a multicylinder engine, embodying the features of this invention,

Figure 2 is a vertical section of the fuel injection pump and the end portion of the engine base showing the driving connections for the pump,

Figure 3 is a vertical section. through the pump cylinder and the passages leading to and from the pump for conveying the fuel oil, and

Figure 4 is a side elevation of the engine, parts being broken away to show the governor controlling the by-pass valve associated with the pump, and the driving connections therefor.

Referring to the drawings, there is illustrated an engine having a base A upon which are mounted a plurality of cylinders B, as for instance six, each operating on the principle disclosed in U. S. Patent No.'

1,517,015 of November 25,-1924,'granted to \Villiam T. Price, each of the cylinders B being provided with a head C within which are housed suitable valves operated by the push rods D. Preferably the cylinders B- are water jacketed, being connected by a suitable pipe E with a water pump F driven through suitable gearing by the drive shaft G of the engine. Y

The fuel, which maybe of 'any suitable liquid, such as fuel oil, is fed selectively to the cylinders B through the medium of a distributor H of the type described in copending application Ser. No. 708,835 filed April 25, 1924:, havin tubes J leading to the injection nozzles l Fuelis supplied to the distributor H from a pump shown in detail in Figures 2 and 3, which is mounted onthe forward end of the base A in the manner hereinafter described. 7

The fuel pump includes a frame L upon which is supported in any suitable manner, as by the stud bolts 0, the block P within which there is a chamber Q having an inlet B through a valve seat S, held in the block P by means of a screw threaded bushing T. An outlet for the fuel oil is provided in the passage U leading from the chamber Q through a suitable check valve V to a tube W connecting the pump to the distributor H. There is also provided a by-pass X as-' sociated with the outlet W, through which fuel in excess of the quantity required is led back to the fuel supply source. The opening to the by-pass X is controlled through the medium of a by-pass valve Y preferably constructed to operate in the manner described in copending application of William T. Price and George J. Rathbun, Ser. No. 399,- 993, filed July 29, 1920. The by-pass valve provides a means to vary the duration of the fuel injection period. The pump is provided witha plunger Z reciprocating in an accurately bored guide at extending through the frame L and having a flange b by which the guide is rigidly held between the frame L and the block P. At the inlet R there is provided a check valve 0 which is drawn open upon the downward stroke of the.

plunger Z and is closed on the upward stroke thereof. Suitable fittings are provided by the nipple d and the pipe connection 6 for a pipe leading from a reservoir of any desired construction to conduct the fuel oil to the pump chamber Q.

The plunger Z is reciprocated by an eccentric f mounted on a shaft g which is rotated by means of a suitable gearing system such as the gear h and the pinion j. The ratio of the gear in and the pinion j is such as to produce a reciprocation of the plunger for every fuel injection desired, thus,'assuming that the engine illustrated comprises six cylinders operating at a fourstroke cycle, the ratio of the gearing to the pinion 7' will be three to one which means that there will be three pumping strokes of the plunger Z to each revolution of the crank shaft G.-The eccentric shaft 9 may also be employed to drive the centrifugal water pump F associated with the cooling system. The bearing is for the shaft 9 is rovided with a web 0 formed integrally with the end housing p of the engin'e base. An oil seal for the shaft 9 is provided at the point at which the shaft 9 extends through the housing. Preferably the seal is provided by flan es 9 cooperating with pockets 1' formed integrally with the housimmec I ing 3). Additional bearings s are provided at either side of the eccentric f and are supported by extensions t of the housing 9.

The eccentric f is provided with a connecting rod a coupled by means of a wrist pin 1) to a tappet w; in the form of a piston which is adapted to slide in a cylindrical guide :0 formed in the housing 3). The wrist pin 0 is held in place in the tappet by means of suitable bolts y. In the upper face of the tappet w there is provided a small block .2 set into the tappet and adapted to bear against the adjusting member 2 fitted on the end of the plunger Z and adjustable with respect thereto by means of a nut 3 and cooperating threads 4 on the end of the plunger. The adjusting member 2 may be adjusted with respect to the plunger Z by turning the nut 3 thereby causing the adjusting member to be moved longitudinally in the desired direction on the end of the plunger Z. The eccentric f through the medium of .the tappet w and its associated parts, as above described, forces the plunger Z upwardly. The down stroke of the plunger Z is caused by a coil spring 5 bearing on its In operating an engine of this type it is usual for the injection to take place during only a fraction of the cycle. For instance, it may be desired to limit the injection of fuel into the cylinders to say 20 of one revolution of the crank shaft. It is evident that with a pump constructed as above described, the plunger Z is operating continuously and that during one of its strokes it is continuously pumping, the other or return stroke being a suction stroke. Since in this particular case the pump shaft 9 is rotating three times as fast as the crank shaft G, each pumping operation of the plunger Z occupies one sixth of a revolution of the crank shaft, that is to say, 60. Such a long injection is ordinarily not. desired and therefore a portion of the pumping stroke of the plunger Z may well be eliminated. Heretofore this has been done by actuating the pump plunger by means of a non-circular cam. "However, due to inherent advantages of employing a circular cam or eccentric for operating the plunger, additional means are employed to nullify the effect of the unof the stroke in which it is desired to pump no fuel through the "outlet W. This means includes a pair of hooks 10 and 11 adapted .to engage with each other, the former being.

which bears against the face of the plunger Z and the other against the inlet valve a pressing in the part, as it were, and tending to press the valve-c to its seat to close the inlet Thus as the plunger Z descends on its suction stroke, its hook 10 will engage the hook 11 on the inlet valve 0 to unseat the valve and 'educethe resistance to inflowing fuel. At the time when the plungerZ is at the lower, limit of its stroke, the inlet valve 0 is being'held open and remains so until the plunger Z reaches the predetermined pointat its upward stroke whereupon the hooks 10 and 11 mutually disengage, and the injection of fuel from the chamber Q, through the passage U of the pipe WV to the injection nozzles K continues untilthe by-pass valve Y is operated to again relieve the pressure and discontinue the flow of fuel through the supply pipe \V. The time at which the hooks .10 and 11 disengage'may be adjusted by means of the adjusting member 2 con trolled by the adjustin nut 3; that is to say, if it is desired to siorten the duration of fuel injection, the plunger Z may be lowered to the desired degree by means of the adjusting nut 3 so as to produce the effect of keeping the hooks 10 and 11 in engagement for a greater portion of the timing stroke. On the other hand, if it is desired'to lengthen the duration of fuel injection, the plunger Z may be raised by screwing the nut 3 in the opposite direction to shorten the portion of the pumping stroke (luring which the hooks 10 and 11 are in engagement.

The speed or power delivered by the engine is regulated .by the by-passvalve Y which controls the duration of fuel injection either automatically or manually, as desired.

The by-pass valve Y cooperates with a seat 13 and when depressed is adapted to permit the passage of fuel from the pump chamber Q through the check .valve V into passages 14 and thence to the by-pass X, leading to the reservoir on other suitablesource of supply for the pump. The seat 13 and the passages 14 are formed in a uide 15, held in place in %y means of a nipple or bushing 16. The by-pass valve Y is provided with a shank 17 which extends beyond the guide 15 so that it may be actuated at the proper intervals and timing to perform its functions. The mechanism here shown for operating the by-pass valve Yincludes an eccentric 19 on the shaft- 9 for operating a pitman or connecting rod 20 having a sleeve bearing 21 on the eccentric 19, a plunger 22 connected to the pitman 20 by means of a wrist pin 23 and adjustable extension member 24 attached to the plunger 22, a lever 25 pivotally mounted at the end of the member 24 and having a contact screw 26 adapted to bearagainst the shank -17 of the bypass valve Y, and a' movable fulcrum member 28 adapted to bear at any desired point along the curved surface 29 on the lever 25. As the shaft 9 rotates,'the lever 25 is continuously oscillating back and forth about the tip of the fulcrum 28 as the center. This rate of oscillation is the same as the rate of reciprocation of the plunger Z and at a definite predetermined relation thereto; The timing of the'opening of the by-pass valve Y is determined by the extent of the motion of that end of the lever 25 at which the screw 26 is located. A slight amount of play is'left between the point of the screw 26 and the upper face of the shank 17 so that with the fulcrum 28 in its extreme position at arm. to the left of the fulcrum increases.

This causes at the valve Y a quicker and greater opening to release the pressure in the supply pipe WV in proportion as the fulcrum 28 is moved toward the right. .This earlier release of pressure results in reducing the amount of fuel suppliedto the injection nozzles K by decreasing the relative injection period, and a corresponding reductionof power developed by the engine.

The operation of the fulcrum 28 may be either automatic or -manual. If it is desired to maintain a constant speed in the engine regardless of the power delivered, the I fulcrum 28 may preferably be controlled by an automatic governor such as, for instance, of the centrifugal type. Such an arrangement is illustrated in Figure 2 wherein it will be seen that the fulcrum 28 is pivoted on a shaft 31, the center of which is at the cen-. ter of the curved surface 29 of the .lever 25. The shaft 31 is suitably journaled in a frame 32 and has an arm 33 which is attached to a vertical ,rod .34 extending downwardly and attached to a rotating cage-35. A pair of centrifugal governor balls 36 pivotally mounted on a spider 37 are provided at the ends with arms 38 cooperating with links 39 to depress the cage 35-when the balls are extended by centrifugal force. The spider 37 is rotated by a pair of beveled gears-4O and '41, the latter being mountedon a shaft 42 with a gear 43 meshing" with the'gear h in Figure 4. The gear 43 is shown'forwardly of the pinion j, the latternot being seen in Figure 4 because of its rearward position. The shaft 42 is supported partly by a bearing 44 in the web 0. It will be noted that as the speed of thedrive shaft G increases, the

strained by the action of a spring (not shown), and causes the lowering of the cage 35. A corresponding. lowering of the rod 34 occurs, and through the medium of the small arm 33 the fulcrum 28 is moved to the right, Figure 52, causing earlier opening of the by pass valve in the pumping stroke of the plunger Z. The supply of fuel to the injection nozzles K is thereupon reduced and the power of the engine decreases accordingly to result in a tendency to slow up'the drive shaft G.

Occasionally an adjustment may be desirable in the lever 25 due to wear or other causes, and to this end the member 24 is made adjustable longitudinally with respect to the plunger 22. A pair of diagonally disposed'set screws 48 are provided @3- tending through the plunger 22 to contact with angular notches 4.7 in the member 24. The set screws 46 are located at an angle to each other, so that upon loosening one and tightening the other the member 24 may be shifted thereby longitudinally with respect to the plunger 22.

A slight amount of leakage of the fuel oilis usually present in pumps of this character. That which leaks through the joint hetween the guide member a and the pump body P may find its way to the bore in the frame L in which the plunger 22 slides. This oil provides sufiicient lubrication to the bearing surface of the plunger 22 and to The oil which leaks from the pump chamber Q out through the slight space between the guide a and the plunger Z may find its way through a passageway 51 and a drip 52 into a groove 53 from which the oil may be collected and reused.

The base A of the engine may be provided with plates 55 and 56 which are movable to permit access to the bearings of the connecting rods and drive shaft of the engine. Additional access is also provided by handholes having removable covers 57 on the lower part of the base, as well as the hole covered by the plate 58.

ll claim:

A pump for a combustion engine comprising the combination ot a frame, a shaft having an eccentric, a tappet, a connecting rod connecting said tappet and said eccentric, a b'.ock provided with a chamber and mounted on said frame, a spring pressed plunger in said chamber arranged to be actuated by said tappet, a guide support between said frame and block for said plunger, an inlet, and inlet valve in said chamber inlet, and mutually engaging members on said plunger and said inlet valve to hold said valve open for a portion of the pumping stroke of said plunger, an outlet and a bypass for said chamber.

In testimony whereof I have signed this specification.

GEORGE J. RATHBUN. 

